Device for electric sound transmission



Dec. 6, 1932. H. CHlRElX DEVICE FOR ELECTRIC SOUND TRANSMISSION Filed Nov 1. 1929 4 I 1 I I I IYNVENTQR HEM; cud-R M ATTORNEY Patented'bec. 6, 1932 um'raos'mras PATENT OFFICE mar GRID-HZ, OE PARIS, ml?! 7 10B SOUND MSKISSIOH- A plication fled ll'ovember 1,1929, Serial 10.4034), and in museums: 1?, ms.

The present invention is concerned with the combination and disposition of microphones for the purpose of electric sound transmission.

It is particularly, though not exclusively, applicable to the installation of broadcasting studios and for making phonographic records of musical concerts. a

One of the advantages ofithis invention is the possibility of distributing the musicians of an orchestra in a semircircle around the sound collecting microphone system at a distance relatively unfavorable in regard to the latter, yet without any undue loudeningor muflling of any of the instruments of the ensemble.

Another advantage obtainable throu h this invention is the possibility it affords m a large number of rformers to be engaged 26 in a relatively sma room without impairing the effect of the orchestral ensemble.

A third advanta consists in the avoidance of disturbing e ccts'of stationary waves (strengthening or mufflin certain tones).

These results are obtained, according to the invention, by combining a number" of microlphones in such a manner that the difierout o cments of this ensemble are grouped in a space which is small as compared to the 00 space occupied by the orchestra. The sensitive surfaces of these micro honic elements are exposed in different ircctions, recautions being taken, on the other han to avoid that the elements cover each other or are influenced by sound waves reflected from neighboring surfaces.

she invention will be better understood by referring to the attached figures and to the A descriptions pertaining thereto which, by way at eaamplc, indicate a possible arrange ment. Uzi these figures Figure i represents a plan view;

Figure 2 an elevation of he microphone 1 arrangement; and V Figure 3 is a plan illustrating the location oilfhfi arrangement and of the performers in a a According to Figure 1 two microphones 1 and 2 are placed back to back with their sensitive faces turned out. Instead of this tive face turned at rig t angles to the two absorbing partition 5 of the same qualities .;shown in plan, supposedly of a rectangular location in the hall are negligible, notwitharrangement a single microphone might be employed having two sensitlve faces turned in opposite directions. Near this first group a third microphone-3 is laced with its sensiothers. A vertical sound-absorbing partition 4 is located behind the micro hone 3.

It has a bolstered surface to absorb t e sound waves. Likewise there is a horizontal soundunderneath the microphone ensemble.

Figure 2 shows the same elements in elevation. One perceives by looking at the figure that the microphone 3.is slightly elevated above micro hones 1 and 2 so as not to be covered b t e latter. The microphones are supporte in the usual manner, for instance, on the legs 6 and 7, with the inte "tion ofan insulating holder not depicte on the sketch. 7

Figure 3 indicates how a group of micro- 7 phones 1, 2, 3 combined in accordance with the'invention, may be located in a hall 8,

shape. T e musicians of the orchestra or the performing chorists are arranged in condotted lines, for instance, 9.

The action of the microphones on the electrical apparatus to which they areconnected, for example, modulation amplifiers, or recorders, is intensified by suitably arranged circuit elements such as arallel connections, transformer with multip e primary windings and common secondary winding, etc.

It is evident that under these conditions and owing to the arrangements which con.- stitute the object of this invention the varia. tions in eifect of an instrument caused by its standing the close proximity between the per formers and the microphone s stem. 0n the other hand, the noisy efi'ect o the stationary waves is avoided on account of the fact that the microphones are not rigorously secured in one place. Finally the resence of soundabsorbing partitions has e efiect of exposing the microphones mainlyto direct sound 7 waves at the exclusion of waves reflected from neighboring surfaces, floor and walls.

It must be understood that the invention is by no means limited to the arrangement as shown in this example; it is, in fact, possible to increase the number of microphones used 5 beyond three arranging them in such a manner that they will be turned toward intermediate points of the orchestra, and not only toward the two ends and toward its center as proposed in the example considered above.

Another disposition would be to have the orchestra arranged so that it will completely surround the group of microphones and to replace the microphone 3 with a double-faced microphone or with two microphones back to back similar to the system of microphones 1 and 2. In this case partition 4 evidently has to be omitted.

I claim:

A sound collecting unit for collecting sound emitted by a source or group of sources occupying a zone around sald unit which is large l relative to the dimensions of the'unit, comprising a group of microphones facing in different directions toward said large zone and grouped within aspace which is smallrelative to the size of said zone, and sound absorbing material positioned adjacent the back of .sald microphones and additional sound absorbing material positioned adjacent the bottom of said micro hones, all of said sound absorbing material ing at a distance which is small relative to the dimensions of said large HENRI CHIREIX. 

